The days of chummy tweets are gone, replaced by denunciations of “fake news” by Trump and criticism of the president by Zucker: “The president, and especially the White House press secretary, should understand their words matter. Thus far, they have shown no comprehension of that.”

The irony is striking to those who know them, and those who observe media.

“There is no figure in media more responsible for Donald Trump’s legitimacy in media, which led to his rise in politics and to the presidency, than Jeff Zucker,” media critic Stephen Miller told TheWrap.

Early in the campaign, Trump and Zucker were on good terms, a person who knows Zucker well told TheWrap.

“Donald would say to Jeff, ‘Can you believe I’m going this far?’ Behind the scenes they would kind of joke about it,” the person said. “I don’t think anyone expected it to go this far. They were friendly during the campaign.”

Representatives for Zucker and Trump did not immediately respond to requests for comment from TheWrap.

It started with Zucker plucking Trump from the pages of New York tabloids and putting him on primetime in January 2004. Trump scored good ratings for Zucker as a reality star on NBC all the way through 2017 — and helped CNN’s ratings when he used the show as a springboard to run for president.

Those ratings boosted Zucker’s career, whether or not you believe Trump when he says he helped Zucker get the CNN job.

“Zucker committed the sin of being perceived as a kingmaker, as someone who was at least in part responsible for Trump’s success. That is never tolerated in Trump World,” said Marc Fisher, co-author of “Trump Revealed: An American Journey of Ambition, Ego, Money, and Power.”

“Trump was also miffed that Zucker publicly pushed back against Trump’s repeated claims that he got Zucker his CNN job,” Fisher told TheWrap.

Zucker has boasted that he was key in snatching “The Apprentice” from ABC when executive producer Mark Burnett shopped it to networks in 2003.

“I understood who and what Donald Trump was because I was from New York and I understood that he was just a one-man-wrecking-publicity machine,” he told a Drexel University audience in 2011. “Even if the show wasn’t good, he was going to say it was good. Or… even if the ratings weren’t good, he was going to say the ratings were great, and that nobody could generate publicity like Donald Trump. And by the way, that turned out to be entirely true.”

After Trump declared himself for president in 2015, Zucker’s CNN gave him a windfall of free airtime. The network often ran his rallies uninterrupted, despite Zucker’s past public statements about Trump’s dishonesty.

When Trump announced his candidacy on June 16, 2015, he asserted that “When Mexico sends its people, they’re not sending their best. … They’re bringing drugs. They’re bringing crime. They’re rapists. And some, I assume, are good people.”

Soon after, CNN gave him a forum to clarify those remarks, in an interview with host Don Lemon. Trump cited several news reports that he said backed him up. Lemon politely maintained that the reports were “about women being raped, it’s not about criminals coming across the border.”

“Well, somebody’s doing the raping, Don,” said Trump.

As Trump advanced and it became more apparent he would be the Republican candidate for president, CNN began to fact-check him more aggressively. Trump pushed back against CNN and other media outlets — including in rallies they aired.

“I don’t know of any specific moment when their relationship soured for good, but as Trump discovered during the campaign just how effective his attacks on the media were with his base, Zucker made for a natural target,” Fisher, who is also a senior editor at the Washington Post, told TheWrap.

The relationship was clearly strained by Aug. 2, 2016, when Trump tweeted three times about how upset CNN’s reporting had made him.

On that day alone, CNN ran this story about Trump escalating his fight with the family of fallen U.S. solider Humayun Khan, this story about Trump being mocked for eating KFC with a fork and knife, and this opinion piece calling Trump “ambitious, self-centered and seemingly amoral.”

Trump, who most pundits predicted would lose to Hillary Clinton, wrote: “CNN will soon be the least trusted name in news if they continue to be the press shop for Hillary Clinton… People believe CNN these days almost as little as they believe Hillary….that’s really saying something!”

CNN was far from the only outlet he criticized. But Trump’s beef with CNN was more personal. In September 2016, two months before the election, he called Zucker a failure.

“Jeff Zucker failed @NBC and he is now failing @CNN,” Trump wrote.

Miller, who has harshly criticized CNN, said Trump’s personal relationship with Zucker seems to be a factor.

“He never had a personal relationship with them,” said Miller of Trump’s critics on other networks. “He’s very good at ignoring people on TV he never knew.”

When AT&T began the process of trying to acquire CNN and Time Warner in 2017, Trump’s Justice Department tried to hold up the deal. When the merger went through in June 2018, Trump urged Zucker’s new bosses to fire him.

“The hatred and extreme bias of me by @CNN has clouded their thinking and made them unable to function,” said Trump in August. “Little Jeff Z has done a terrible job, his ratings suck, & AT&T should fire him to save credibility!”

Last month, Zucker suggested Trump’s rhetoric against CNN was partly to blame for the pipe bombs sent to the network.

Today, Lemon routinely criticizes Trump. In August, he accused him of a performance “straight out of a dictator’s playbook.” It was far from the respectful exchange he had with Trump in 2015, about whether Mexico was sending rapists across the border.

CNN’s latest clash with Trump also involved immigration — and disputes over the facts.

During a White House press conference last week, Acosta challenged Trump’s assertion that a caravan of migrants, far from the border, were part of a U.S. “invasion.”

Trump called him a “rude, terrible person.” Then a female White House aide tried to take away Acosta’s microphone, and Acosta maneuvered to keep it.

The White House announced that night that it had pulled Acosta’s credential.

CNN called the revocation of Acosta’s pass “a threat to democracy.” On Tuesday, it filed suit, demanding he be allowed back at the White House to do his job reporting on the president.

“Looks like a very good, legitimate First Amendment lawsuit,” First Amendment attorney Barry Covert, who thinks the Trump Administration will back down, told TheWrap. “Any decent, competent lawyers or counsel to the president would have advised him against this.”

The person who knows Zucker said the conflict between Trump and Zucker may have started as a game.

“I think it went past being a game when it started being a little dangerous,” the person told TheWrap. “I think it stopped being a game and I think Jeff certainly knows that. I do not believe in Jeff’s mind it’s a game anymore.”